Feed roll control system for a forage harvester

Abstract

A system to control the position of one or more feed rolls in a forage harvester. The system includes at least one fixed feed roll arranged to rotate around a rotation axis which is fixed with respect to a chassis of the harvester, and in cooperation with the at least one fixed feed roll, a movable feed roll arranged to rotate around a rotation axis which is movable towards or away from the corresponding fixed roll. The system determines various parameters, including input data for the driving force exerted on the rolls, position of the movable feed roll, and rotational speed of the drive shaft, and inputs the data to a control unit, which provides commands to one or more valves and to one or more throttles to control the movable feed roll via the hydraulic piston/cylinder arrangements.

1. A system for controlling the position of one or more feed rolls in a forage harvester, the harvester comprising at least one fixed feed roll arranged to rotate around a rotational axis which is stationary with respect to a chassis of the harvester, and at least one movable feed roll arranged to rotate around a rotational axis which cooperates with the at least one fixed feed roll, and is movable towards or away from the corresponding fixed feed roll to move a crop therethrough, the system comprising:
 at least one piston/cylinder arrangement arranged to control movement of the movable feed roll towards or away from the corresponding fixed roll; 
 a hydraulic pressure source and at least one hydraulic connecting line positioned between and connected to the hydraulic pressure source and the piston/cylinder arrangement; 
 input data from a plurality of sensors including rotational speed of a drive shaft of the movable feed roll, position of the movable feed roll, and driving force, 
 wherein the driving force is determined by at least one of
 a) torque of the moveable feed roll, or 
 b) pressure difference between a hydrostatic drive and return lines of the hydrostatic drive, and 
 
 a control unit configured for receiving the input data of the rotational speed of the drive shaft, the driving force, and the position of the movable feed roll, the control unit further configured to calculate a command signal as a result of the receipt of at least one of
 a) input data of the driving force and the position, or 
 b) input data of the rotational speed of the drive shaft and the position, the control unit configured to send one or more command signals to control at least the moveable feed roll; and 
 
 an apparatus to actuate movement of the movable feed roll in response to at least one command signal, the apparatus including
 a) a valve configured to control hydraulic pressure in the piston/cylinder arrangement, and 
 b) a throttle configured to damp hydraulic pressure in the piston/cylinder arrangement. 
 
 
     
     
       2. The system according to  claim 1 , wherein the plurality of sensors includes a pressure sensor for measuring pressure data in the piston/cylinder arrangement, and wherein the control unit is configured to calculate a desired pressure in the piston/cylinder arrangement as a function of receipt of driving force data as well as position and pressure data, and for sending out command signals to the apparatus in order to obtain the desired hydraulic pressure. 
     
     
       3. The system according to  claim 1 , further comprising at least one hydraulic accumulator arranged in connection with the hydraulic line. 
     
     
       4. The system according to  claim 1 , wherein the movable feed roll is driven by a hydraulic motor and the driving force input data further includes the pressure in the hydraulic line to the motor. 
     
     
       5. The system according to  claim 1 , comprising a front and a back set of feed rolls, each set comprising a fixed lower feed roll and a movable upper feed roll, the movable upper feed roll of the back set being connected to the harvester by pivotable arms, the upper feed rolls being connected together by connecting rods. 
     
     
       6. The system according to  claim 5 , wherein the plurality of sensors includes a sensor for determining the rotational position of the arms.